Doomsday Dimensions
by tinuvielb
Summary: Rose meets the parallel Doctor in her parallel universe. A journey to Gallifrey unravels a mystery involving an ancient shield, a deadly epidemic, and the Doctor's old nemesis, the Master. Can the Doctor save his people? Can he save Rose?
1. Chapter 1

"Doctor! Doctor! Are you there? It's me, Rose! Open up!"

She hammered furiously at the TARDIS door. Once, the Doctor had told her it would keep out the assembled hordes of Genghis Khan; at the time she'd been impressed. But right now, if it could keep _her_ out, that would be something.

She had almost got used to his being gone. The daily routines of work and family had become progressively more real; her time with the Doctor a dream that faded day by day.

That is, until this morning, when she had awakened to the sound of time and space being forced apart: the sound of the TARDIS. In her mad dash to get outside, she had stumbled and scrambled and, quite literally, fallen down the stairs. It didn't matter. She couldn't feel anything but joy. She couldn't think anything but: "It's him. He's come back."

A muffled voice echoed from within the TARDIS, and grew louder. "Hang on a minute, I'm coming, I'm coming--oof!"

The moment the door had opened, Rose had leapt, wrapping her arms about his neck, squeezing him tightly as if to prove he was real. A moment later, he returned her embrace. Presently, however, she became aware of a slight gasping sound. In a strained voice, he said, "You're hugging me a little too tightly, my dear."

"Sorry!" Laughing, Rose released her grasp slightly and gazed up into his twinkling blue eyes.

They were the wrong eyes. In the wrong face.

"Well," he said, breathlessly. "That's rather an enthusiastic way of saying hello for the first--"

She gaped at him in astonishment. "You're--you're not him--you're not the Doctor! " Immediately, she pushed past him into the TARDIS and called, "Doctor, are you in there? Doctor, where are you? Doctor!"

A voice behind her said, "I'm right here. I am the Doctor. No, really, I am. Is there some way that I can help you?"

Rose turned and looked at him. He was a Byronesque figure with a sensitive face and a halo of long ringlets. He wore a long frock coat, a brocaded waistcoat, and a silk cravat. He seemed to be blushing slightly, and smiled at her with a bemused expression. In an instant, she realized what had happened. She laughed, relief and joy spilling over her once more.

"Of course it's you...of course. You've regenerated. But," her expression clouded, "that means you died, didn't you, and came back. Did you die trying to cross the Void? Trying to find me? I'd tell you you shouldn't have done it, but, honestly...I'd have done the same for you,"

"Oh dear," said the Doctor, twisting the chain of his pocket watch between his fingers. "This is awkward."

"No, it's all right," said Rose, taking his hand. "I've got used to the changes by now. Your new face...it's older, but...it'll be fine, really. What's important is that it's you and you're back." She hugged him tightly once again.

"This is very awkward," said the Doctor again, after catching his breath. He raked his fingers through his hair and glanced away. Rose recognized the familiar gesture and beamed.

"I told you," said Rose. "It doesn't matter, you look okay, really, I don't mind, honestly--"

"Time travel can be _exceedingly_ awkward," he interrupted. "Especially when you meet..." He fixed his gaze upon Rose. "Especially when you meet a person whom you haven't yet had the pleasure of meeting."

Rose blinked at him, uncomprehending.

"Let's start again. I'm the Doctor. What is your name?"

"Rose," she murmured, starting to understand.

"Rose," he repeated. "Rose, Rose, Rose. Hmm." He stroked his chin, thinking. "There's an echo of familiarity there...not a memory exactly, but definitely an echo." The Doctor smiled at Rose. "Yes, I think it's quite probable that we will have met at some point in the future. My linear future, that is, actually. We might have met in the past."

"An echo? That's all you remember--an echo?" Rose asked, astonished. "You don't remember...us. You don't remember anything that we... No. No, of course you don't, because it hasn't happened yet. And maybe," she continued, her voice beginning to crack, "Maybe because I've met you now, it's changed something...and I won't ever...we won't ever..." Joy turned to despair. Hot tears stung her eyes. She began to weep.

For a few moments the Doctor shifted uncomfortably from foot to foot, watching her cry. Then, somewhat clumsily, he pulled her into an embrace and patted her.

"Why did you come here," she sobbed, "If it wasn't for me? You said it was impossible to cross between parallel universes."

"Oh, not impossible," he replied. "Just a lot of paperwork, really. Three to six months later, if they haven't lost any of the forms and they don't have any niggling questions and the moons are all in the right phases and if you've paid the proper fee, the Time Lords will condescend to send you a Dimensional Visa, and off you go. More trouble than it's worth most of the time, if you ask me. In any case, I'm afraid I don't quite follow; I haven't crossed the Void--not to get here, at least."

She stepped back, confused. "But you said the Time Lords were all dead and couldn't open up--"

"Time Lords--_dead_?" He gazed at her in horror. "What are you talking about?"

She put her hand over her mouth. She understood. "You're not my Doctor. You're like...Rickey or Pete. You're _this_ universe's Doctor."

The Doctor blinked at her for a moment, perhaps wondering who Rickey and Pete were. Finally, he smiled brightly and said, "Yes, I am the Doctor." He bowed with a flourish. But when he straightened up again, he was frowning. "Now, Rose, kindly explain what you said about the Time Lords being...dead."

"They were all killed in a War. The Time War. You--well, _he_ is the only one left, in his universe."

The Doctor faltered at the enormity of this revelation. Then, recovering, he shook his head vigorously. "No. You must be mistaken. It's completely, utterly impossible. Perhaps all this excitement has been too much for you. You need some rest. Why don't you lie down for a--"

"I probably shouldn't have mentioned it," said Rose. "I know...if you go mucking about with time too much, try to change the past, the Reapers will come and--"

"Reapers!" cried the Doctor. "Reapers! Nonsense! The very idea! Reapers are held safely beyond the Void--"

"--By the Time Lords, I know," interrupted Rose. "But in my world...my old world, there aren't any Time Lords."

"No Time Lords...it's unimaginable...a universe without Time Lords." The Doctor paced the Control room, his expression grave. "It's been some time since I've been home, you know," he mused. "It's a stuffy, boring old planet, not interesting in the least, but still...it's home. Should stop and say hello...perhaps have a look round to see if...no!" He laughed and waved a hand. "Poppycock. Ridiculous. Nothing could ever punch through Gallifrey's defences. But still," he nodded to himself, "I think I will go home...just for a visit."

"I'm coming with you," said Rose.

The Doctor glanced up surprised. "What? But we...I mean, I'm not--"

"I know," said Rose. "You're not him. It doesn't matter. He's never coming back, he can't come back, he told me so himself. He told me goodbye. Him and me, we had...we had a laugh. But it's over. You aren't him, you aren't _my_ Doctor, but you are the _Doctor_, and this is the TARDIS. I belong here. So I'm coming with you, and that's final."

"I can't change your mind? You are resolute? Absolutely decided?"

"Yes," said Rose defiantly.

"Marvelous!" The Doctor broke into a wide grin as he twiddled the TARDIS dials and set it in motion. "I do despise travelling alone. As I remarked once to another young person of my acquaintance: somewhere there's danger, somewhere there's injustice, somewhere else the tea's getting cold. Come on Rose; we've got work to do."


	2. Chapter 2

"Gallifrey is tedious," the Doctor said. "Getting there even more so. This may take a while. You may as well get--I say, are you all right?" He gazed at her with a worried expression.

"What?" Rose asked, puzzled. Then she glanced down. She had scrambled directly out of bed, and was only wearing pyjamas, the bottoms of which were muddy at the ankles. One was ripped at the knee and stained with dried blood. She recalled, slightly, that she might have fallen down the stairs in her dash to get to the TARDIS. She put a hand to her head; much of her hair seemed to be sticking straight up. She was fairly certain that her nose was red and her face tearstained.

"I must look a fright."

"Not at all," he replied, gallantly. "But there is a wardrobe past the--"

"I know."

"And a first aid kit in the--"

"Got it."

"And a spare bedroom--"

"I'm already there."

In retrospect, Rose realised, she should have asked for directions. Endless stairs, bookcases, and even _bats_--nothing was right about this place. She hadn't even been able to find the shower; so now she was sitting surrounded by bubbles in an enormous claw-footed bath. "Here I am again," she thought to herself. "Taking off across the universe with a man I don't even know." She felt a sudden pang of guilt: she hadn't told her mum, Mickey, or even Pete where she was going. Her family, the people who ought to matter most to her--she'd left them all behind--again--without a second thought. She closed her eyes and sank into the hot water.

"Rose."

Startled, Rose opened her eyes. "Doctor!" He was standing in front of the bathtub.

"Sorry to disturb you, but I need to ask you a question: in your travels with the--er--other Doctor, did you ever happen to acquire a trans-temporal passport? It's just that we're at the border, and--"

"N-No," she stammered, sinking down lower and hoping the bubbles hadn't all dissolved. "I haven't got a...trans-temporal passport. I've got a British passport, but that's at home."

"Oh dear," said the Doctor, leaning against a wall and stroking his chin. "That complicates things somewhat..."

"Look, do you mind? I'm in the bath!"

He seemed genuinely surprised at her tone, and shot her a puzzled look; an instant later, his eyes widened as if something very obvious had just occurred to him. "Oh! Right! I forgot. I'm--I'm terribly sorry!" He averted his eyes and was out of the room in an instant, quick enough to avoid the sponge Rose had chucked at his head.

Some time later, Rose reappeared--fully dressed--in the Control Room. The Doctor was involved in a heated discussion with someone on the view screen.

"No, I have not been asked to carry anything for anyone else. Yes, I packed my own bags. Yes, my TARDIS has been in my control..." There was a pause. "I am travelling with a non-Gallifreyan. No, she doesn't have a passport." Another pause. "Look, I can vouch for her. She constitutes no threat to advanced civilisations; she's a primitive--just yesterday her people were swinging from the--what? Human. Yes, that's right, human. H-U-M-A-N. _Homo sapiens_. Earth. Yes, I can hold." He flipped a switch, turning off view screen. "Fat, useless bureaucrats," he muttered to himself. "Blowing them up would be a public service--oh! Hello, Rose."

"Are we going to be able to get through?" asked Rose.

The Doctor sighed irritably. "Gallifreyan xenophobia is second only to Gallifreyan bureaucracy. Unless I can get some strings pulled, I'm foreseeing a three hundred-page application, six month waiting time--"

"Three _hundred_ pages?"

"Welcome to Gallifrey," he said, smiling wryly.

"Is it also a Gallifreyan custom to walk in on someone In the bath? Because where I'm from, you don't just go barging in--"

"Ah yes, that," said the Doctor, fiddling with his watch chain. "Er...given the fact that there are no fewer than 16 billion intelligent life forms in the universe, all with their own sets of complex social customs and taboos that vary by decade, it's not entirely inconceivable that, on rare occasions, I might err in--"

The view screen whistled. Perhaps grateful for the interruption, he immediately swung around and flicked it on. "Yes. Yes. Yes. Yes. No. Fifteen. Yes. Yes. Yes. Not a problem. YES!" The Doctor punched the air.

"What?" Rose leaned forward, trying to see what was on the screen.

"It helps to have a few connections. Councillor Romanadvoratrelundar took care of everything. But...ah...there is one very tiny complication." He turned away, avoiding her gaze.

"What?" asked Rose.

"Just a...formality, really," he stammered.

"What?"

"It's nothing. A minor inconvenience."

"_What_?"

"Er...you've got to go through Customs."

-000-

"Ah, there you are," said the Doctor, brightly. "That didn't take long, did it? Not too terribly--"

"THAT was a 'minor inconvenience'?" Rose hissed as she stalked away from the Customs area.

"Well...er...I haven't actually been through the process, but I understand--"

"I've been probed, prodded, scanned, scrubbed, and scraped. I've had everything searched, and I mean _everything_. They took blood, saliva, sweat, hair, skin, urine...and poo! They wanted a poo sample! What do they want with my poo?" If Rose had been any angrier, she might have burst into flame.

"I'm terribly sorry, really I am. Anyway, you're through the worst of it. The exit requirements are--"

"WHAT?" she cried. "Exit requirements? Do you mean I've got to go through all that again when we leave?"

"Ah..." The Doctor twisted his watch chain through his fingers; then suddenly pointed at the amber sky. "Look at that! Marverlous! Such lovely weather. Come along now, Rose, the capitol is this way."

-000-

Rose stood in the marble antechamber, gazing up at the doors. How tall were they? Twenty, thirty feet? They swung open with an eldritch groan, pulled by bizarrely-attired guards.

"What are they wearing?" Rose whispered. "Silly hats and dresses?"

The Doctor shushed her as they were ushered forwards into a dark, wood-paneled office. A blonde woman sat at an ornate desk. Hanging behind her was a splendid gold shield, encrusted in jewels.

"Romana!" cried the Doctor. "So good to see you! It seems like only yesterday that you were screaming for my help and now--oh! Is that--no, it can't be--"

The shield of Rassilon," said Councillor Romana, smiling.

"But how? It was destroyed--" said the Doctor.

"We have found a proof for Eulenberg's conjecture."

"Ridiculous! Eulenberg's conjecture is unprovable," insisted the Doctor.

"Not if you correct for multiversional dimensional flux."

"What are you talking about?" asked Rose.

The Doctor sighed impatiently, "She means it's now possible to travel through Gallifrey's early history. Which is, of course, impossible."

"We do it mostly for archeological purposes, you understand," Romana added. "We snatch important artifacts moments before they are destroyed. We're reluctant to do anything else, as I'm sure you understand."

"Yes, quite," said the Doctor, appearing a bit unnerved.

"In any case," Romana continued, "it's a happy coincidence you're here. We were about to summon you, but it proved unnecessary."

"Summon me? Why were you going to summon me?" the Doctor asked.

Her expression turned grave. "You hadn't heard? About the contagion? No, I suppose not. You're always off exploring, oblivious to what happens here at home."

"You, of all people, should know that--" started the Doctor, but Romana waved him off.

"No matter. We caught the man behind it, and he's safely in custody. An old acquaintance of yours, actually."

"Who?" asked the Doctor, his eyes wide.

Romana smiled grimly. "The Master."


	3. Chapter 3

Councillor Romana glanced at Rose, apparently noticing her for the first time.

"Who is your friend?" she asked.

"Hmm?" The Doctor answered, absently, evidently still taking in Romana's news about the Master. "Oh...that's Rose. She claims an acquaintance with my dimensional doppleganger." He winked at Rose, "Actually, rather more than an acquaintance, I think."

"Sounds interesting. You'll have to tell me all about it," said Romana, airily. She stood up, resplendent in her glittering, high-collared Gallifreyan robes. "But I expect you'll want to see the Master first."

"Him? No, not at all. What a tedious way to spend an evening. I've far more important things to do."

"Such as?" asked Romana.

The Doctor stood as well, and took her arm. "Why...dinner with an old friend. Yes, a _very_ old friend. A very, very, very _old_ friend. Speaking of which, how old are you now, Romana? Four hundred? Five? Oh, don't say six, six is such an awkward age..."

"I am two hundred and seventy-three, thank you very much," she sniffed, pulling her arm away.

"Are you really?" he asked. "Marvelous! I say, you don't look a day over three-thirty..."

Romana scowled and the Doctor teased, all the way to the Official Dining Room. Rose thought she was going to be sick. At first she felt a flash of jealousy; but said to herself, "He isn't my Doctor, he's someone I've just met."

At dinner, Rose began to have great sympathy for Mickey. She now understood very clearly why he had chosen to stay in a parallel universe full of Cybermen rather than listen to Rose and the Doctor enjoy private jokes and laugh about old times. Occasionally she would ask questions, and was very graciously answered. But Romana and the Doctor seemed always to smile at her with an air of indulgent condescension. Rose felt like a little girl at the grown-ups' table.

Presently, Romana and the Doctor left off reminiscing and began to discuss more recent matters.

"Tell me about the contagion," asked the Doctor.

"It started at the Academy," Romana answered. "The whole archeological team was suddenly taken ill. Well, naturally, we assumed something had gone wrong with the temporal calculations, but then we caught the Master trying to steal the shield of Rassilon. He confessed to using a bio-weapon to cause chaos so that he could get into the artifact room. He has thus far been reluctant to provide us with the antidote, despite our best efforts to...ah...persuade him. So far, no one has recovered, and half have died."

"Died?" The Doctor leaned forward, his eyes wide. "You mean--died, then regenerated."

"No," said Romana. "Died. Fifty per cent mortality--at least, maybe more. Shocking. That's why we were going to summon you. But then, as I said, we caught the Master and the outbreak ceased. You showed up anyway. Perfect timing, as per usual."

"I'm so terribly sorry," said the Doctor. "It sounds as if you've had an awful time."

"Yes, quite." Romana yawned, suddenly.

"Are we keeping you up?" asked the Doctor.

"Yes, I should think so," said Romana, rising. "It's been chaotic lately. I hope you don't mind if I beg off early."

"Not at all," said the Doctor. "I'll walk you back to your rooms." He stood, and put her hand in the crook of his arm. This time, she didn't resist.

Rose, watched them leave. Then, not having anywhere else to go, she started after them, though keeping a great distance. She didn't particularly want to hear what they were discussing. They stopped at what must have been the entrance to Romana's apartments, and continued to talk. Rose wandered away; then became aware of a commotion at the other end of a long, marble hallway. "Anything's better than this," she thought, and headed towards the noise.

A Gallifreyan guard was standing in the middle of the corridor, moaning. His semicircular flanged helmet was askew, and he was flapping his robes like a gigantic bird. His eyes were wild and staring. Rose recognised him as one of the guards that had been stationed outside Councillor Romana's office.

"Are you all right?" Rose asked. "What's the matter?"

"They've come!" he cried, pointing into the air. "Daleks! They're everywhere. They're killing all the Time Lords! There's no escape, we're doomed!"

Startled, Rose looked about, but all she could see was an empty corridor. "There's no Daleks here. No Daleks at all. It's just us. You're safe. You're having a nightmare or something."

"Exterminate!" he cried. "Exterminate...EXTERMINATE!" He collapsed, insensible, into Rose's arms. His helmet fell off with a clang. She lowered him to the floor.

"Help!" she cried. "I need some help! Someone's just collapsed! Help! DOCTOR!"

Immediately she heard the sound of running feet. She turned, expecting to see the Doctor. Instead she came face to face with a group of people dressed in what looked like white space suits.

"Biohazard team," a muffled, electronic voice said to her. "Stand aside."

They bundled the fallen guard onto a stretcher, then sealed him into some sort of white vehicle that then whirred quietly down the corridor.

"Did you touch him?" asked one of the space suits.

"Er...yes," said Rose. She felt suddenly cold.

"Rose! Rose!" The Doctor came skidding up the corridor. Several of the white space suit team blocked his way.

"Took you long enough," Rose called to him. She shivered.

Space suit man pulled out a long, glowing probe and waved it in front of her body. Then he turned away, abruptly, and moved towards the Doctor. At that moment, she was overcome with fatigue. She sank to the ground. She became dimly aware of a conversation.

"Do you know her?"

"Yes," said the Doctor, "She's--"

"Human?"

"Yes."

"Doesn't stand a chance."

"_What_?"

"Look," said the metallic space suit voice. "Fifty per cent mortality for Time Lords. She's got a primitive immune system. She'll be dead in a few hours. We can't take her to to hospital, it's too crowded, we're in Triage. We can only admit someone who've got a chance at survival."

"But...can't you...can't you help her at all? She's just a child!" cried the Doctor.

There was a quiet conversation she couldn't hear. Then: "We're going to have to seal this area off."

She opened one eye. The space suit team was creating a sort of hard barrier around her, closing her in. "Doctor!" she gasped. "Don't let them leave me here! Doctor!"

"Rose, I'm going to--"

Just then, another team of white space suits jogged by. She heard the Doctor say, "Hey, where are you going? Councillor Romana's apartments are that way! No--wait!" More footsteps, and his voice trailed away. Then, nothing.

She was sealed in. If ever she had needed any proof that this Doctor was absolutely not _her_ Doctor, this was it. He had left her here alone, lying on a marble floor, to die.


	4. Chapter 4

Rose felt a wave of nausea rising. She threw up on the floor. A few seconds later, she heard an odd creaking noise. She glanced towards it. A featureless white sphere, about the size of a cantaloupe, seemed to be growing from the wall of her prison. It dropped to the floor, and rolled towards her. With a slight cracking noise, it opened. Another white sphere, about the same size as the first, rolled out of it. Then another, and another.

"Bigger on the inside," Rose thought wryly.

Soon she was surrounded by white spheres. They wobbled, then stood up on silver legs. They had arms, too--multiple arms ending in bizarre, shining protuberances. Bulbous eyes flicked open. They stared at her for a moment or two, then began advancing towards her slowly, their silver legs clicking on the marble floor.

"What are you doing?" asked Rose, becoming increasingly unnerved. "Wait! Stay right there! No! Don't touch me! NOOOOOOOOOOOO!"

Meanwhile, the Doctor watched helplessly as a Romana-shaped stretcher was loaded into the ambulance and whisked off. He considered hoisting himself onto the back of it and following her to the hospital. But he couldn't just abandon Rose to her fate. There must be another way.

There was. The confessed author of this disaster was sitting comfortably in the Citadel Gaol. He had put off having a chat with the Master; perhaps now was the time.

As he entered the maximum security holding area, the Doctor suddenly felt very cold. He thought it might be a trick of his imagination--until he realised he could see his breath. Presently, he heard a familiar voice growl, "I heard you were here. Knew you'd come down eventually. Here to gloat?"

"Here to marvel, actually," The Doctor replied, stepping into the solitary confinement area. "After being thrown into a black hole, most people have the decency to die. But you--" The doctor broke off abruptly, shocked by the Master's appearance. He sat alone in a featureless, brilliantly-lit white cell. The deep hollows of his eyes receded in sharp relief to the gaunt angles of his face. He was clad only in a short, thin shift, and shivered constantly against the cold. The Doctor studied him for a moment, not quite believing that his erstwhile friend and great archenemy could be so abjectly reduced. "What has happened to you?"

"Torture," hissed the Master. Seeing the Doctor's expression of disbelief, he continued, "Yes, they've been torturing me. Do not look so surprised. Cold, starvation, sleep deprivation..."

The Doctor slowly shook his head. "I...I pity you. I know I shouldn't. If anyone deserves this treatment, you do--but still..." The Doctor moved closer to the cell. "End this," he whispered urgently. "End your suffering--end your victims' suffering. Please, give me the antidote."

"Are the Time Lords dying?" asked the Master, his black eyes glittering. "Friends of yours, perhaps? I can only hope."

"Yes, friends of mine!" cried the Doctor, angrily. He glanced away for a moment, regaining his composure. "How will their...deaths help you? How can you possibly hope to gain? What do you want?"

"I want to be free of this place," snarled the Master. "And, since you are asking, I want the shield of Rassilon."

"Why--why the shield, particularly?" The Doctor regarded the Master with curiosity and suspicion. "It has no special powers, as far as I'm aware."

"You are aware of very little. The shield is rumoured to be the ultimate weapon," murmured the Master. He leaned forward, his face separated from the Doctor's by only mere inches and a force field. "By the way," he murmured, "what's happened to _you_? You don't look well at all."

The Doctor was startled. He'd been feeling tired since dinnertime, and was now positively exhausted. He had attributed it to the lateness of the hour, but...

"Pallor and fatigue, Doctor. Those are the very first symptoms of the contagion, or didn't you know?" The Master smiled unpleasantly. "I've dreamt of so many ways of killing you, but this is almost tragic. The celebrated Doctor, brought low by a microbe--oh, the irony. However, now that I think of it, I am not yet ready to lose my most worthy adversary--not like this, at any rate. Help me escape, and you'll have your antidote."

The Doctor laughed incredulously. "What kind of fool do you think I am?"

"A desperate one. If not for yourself, then for your friends."

Some time later, the Doctor and the Master were pushing their way down a narrow shaft. The escape had been disturbingly easy to manage: A repeating loop set up on the monitoring cameras, the force field breached without setting off the alarms, and then a detour into the ventilation system. Possibly it helped that both men had had quite a lot of experience at breaking and entering. Things had got a bit tricky when the Master insisted on retrieving his personal effects. He had, at the Doctor's insistence, merely incapacitated the guard who surprised him, rather than killing him. Afterwards, the Master handed the Doctor a long, metallic tube, sealed at both ends.

"Here it is, the antidote," said the Master. "Proof of my intentions. But don't betray me just yet; you'll need my instructions to open it."

On they pressed forward for what seemed an eternity. Finally, the last grate popped free, and they dropped down onto the floor.

"Now, the antidote," said the Master. "Put your hand on either side of the tube and twist."

The Doctor eyed the Master grimly. "This is a trick...some sort of trap. I know you..."

"No, you don't know me, not now, not anymore. In that prison, Doctor, I was tortured. I've never been tortured before. The experience has given me..." He frowned and looked away. In a quieter voice, he continued, "It has given me a new perspective. There has been too much suffering here already. Let me be of some good, finally, in my life. Use the antidote."

With a deep sigh of resignation, the Doctor twisted the tube. Immediately, it glowed hot in his hands, emitting a scintillating energy beam that engulfed the Master. Then tube and Master disappeared, leaving behind only his evil, echoing laughter.

The Doctor stumbled back against the wall. He had known the Master was treacherous, but still he had trusted him. No--he hadn't trusted the Master; but he had allowed himself to hope...what? That some small part of the Master wasn't entirely unredeemable? No matter. There had to be another solution; there almost always was. He would find it. But perhaps he would sit down for a little while and rest...yes, sleep would do him good. The back of his mind protested wildly--every moment he wasted meant less hope for the girl under his protection. But his unnatural fatigue was irresistible...

The Doctor awoke to a metallic clicking noise. He opened his eyes. He was surrounded by little robots with white spherical heads, spindly silver bodies, and enormous, bulbous eyes, which all turned and looked at him when he stirred. They moved towards him slowly.

One of them rolled back his sleeve, rubbed his arm with an alcohol swab, and injected something. Immediately he began to feel a little better. "Nursebots," he murmured.

"Is that what they're called?" said a voice. He glanced up.

"Good morning Rose," he murmured, absently. He paused for a moment; and then it dawned on him.

"ROSE! You're alive!" He jumped to his feet, threw his arms about her, and spun her about.

"Yeah sort of," she said, when she had caught her breath. "No thanks to you. Where were you last night? You ditched me--"

"No, I didn't!" he exclaimed excitedly. "I was trying to find...yes, well all right, I suppose I did, but the important thing is, YOU'RE ALIVE!" He cupped her face in his hands, and gazed at her in wonder. "So--how did you manage it?"

Rose had been extremely angry at the Doctor for abandoning her, but this open demonstration of joy was disarming. "I...I don't know," she stammered. "I was sick, really sick all night, and...then I was better."

"Marvelous!" he pronounced, then staggered.

"Are you all right?" Rose asked.

"I'm fine, wonderful, couldn't be better," he insisted. Then he glanced down and saw that the nursebots were assembling a sort of stretcher. "No, really, I don't need that, I feel..."

He collapsed. The nursebots caught him neatly, and then clicked off down the corridor.


	5. Chapter 5

"_This_ is the hospital?" asked Rose, incredulously.

She had imagined that the Hospital in the Gallifreyan Citadel would be a grand and imposing edifice, all marble and soaring ceilings, with names of major donors engraved on brass plates. Or, failing that, a glittering marvel of advanced alien technology, all glass and brushed steel. Instead, it consisted of a single, dingy ward room, and had the the appearance of something hastily cobbled together: a crowded ring of mismatched beds, overflowing with patients. A twist of cables led from each bed into a central command station. Rose was sitting on an improvised chair--a packing box--near the Doctor, whose body was encased in a flexible biohazard forcefield. This was a measure against contagion, but, as had been explained to Rose, not a guarantee.

"We're doing the best that we can...under the circumstances," apologised the harried young physician, as he finished examining the Doctor.

"Yes--I'm sorry," said Rose immediately. "I know you're working hard, Doctor...?"

"Dr Caligarian."

Rose was actually quite surprised to get a answer to her question. Finally, a doctor with a name!

His examination complete, the physician directed a swarm of nursebots into action. One sent out a stream of long, silvery electrodes that attached themselves to the doctor's scalp. Another located an arm vein, and inserted a thin probe inside. And so it proceeded: each nursebot seemed to be in charge of a particular organ system. Soon the Doctor was covered in a web of silver wires.

Dr Caligarian sat down at one of the command station consoles, and punched up a rotating 3-D image of the Doctor. After a brief study of the image, he made several passes over the console. A moment later, the Doctor's eyes fluttered open.

"Doctor, can you hear me?" asked Rose.

"Everything's collapsing," murmured the Doctor. "Parallel pressure…"

"Delirium," said Dr Caligarian, soothingly. "Give the antitoxin time to work. Just a minute or two, and he'll be..."

"Right!" The Doctor suddenly sat up in bed, his eyes wide. The nursebots skittered about, rapidly rearranging their wires across him. "I'm the Doctor." He pointed at Dr Caligarian, who jumped. "Tell me what you know about this contagion."

The physician stammered, "Er…well, we've only just worked it out. It's a worm."

"What's your name?" asked the Doctor.

"Dr Caligarian. I'm your physician."

"Hmm...that name makes me think you ought to have a...cabinet? Anyway, a worm, did you say?"

"Worms, yes. Microscopic worms. Parasitic helminths. Millions of them. They enter through the skin, migrate through the bloodstream, and then reside in the gut, secreting a neurotoxin. Then they reproduce and exit through the skin again."

"Sounds very nasty. So why can't you kill them? Use some sort of anti-worm medicine--"

"Well, we're able to block the neurotoxin—for a short while, at least. But eradicating the worms themselves is difficult. Once they're in the gut, they encapsulate far enough from any blood vessels that it's difficult for intravenous medications to penetrate. Any toxin strong enough to kill the worm kills the patient, too."

The Doctor gazed about at the nursebots, the force fields, and the command center. "Correct me if I'm wrong, but I was under the impression ours was a highly advanced technological society. Yet you can't kill a worm?"

"Yes….well…you see, there hasn't been an epidemic on Gallifrey for thousands of years," sputtered Dr Caligarian. "No one on staff has ever had any experience treating an infectious disease, much less a parasite. Until very recently, all I ever had to do was set the occasional broken bone!"

The Doctor gestured towards Rose. "She made a full recovery, in a matter of hours. Explain it, Caligarian!"

"What, the human?" asked the physician, surprised. "I can't explain it...humans have a very primitive immune system, they are vulnerable to bacteria, viruses--"

He was interrupted by the wail of a piercing alarm. Dr Caligarian raced to the command console and punched up another 3-D image. Rose recognised the flickering outline of Councillor Romana. He began tapping furiously, gazing at her life sign indicators with increasing dismay. Several long minutes later, the image stablised and the alarm ceased.

The Doctor sank back into the pillows, murmuring bitterly. "If only I'd been able to get the antidote. If only I hadn't allowed the Master to escape…"

"What do you mean, the Master escaped?" asked Rose.

Wearily, the Doctor recounted the events of the previous evening. Rose listened closely to the story, then observed, "It sounds like he used a transmat beam. Why didn't you just reverse it with your sonic screwdriver?"

"With my...sonic _screwdriver_?" asked the Doctor, laughing weakly. "The sonic screwdriver opens doors. Picks locks. Drives screws. Other things you might do with a screwdriver, if it were sonic. It doesn't reverse transmatbeams."

"My Doctor could have done it."

"Your Doctor," he said, eyeing her reproachfully. "Hmmm." He pointed vaguely in the direction of his jacket, which a nursebot had packed away in a cupboard. Rose understood the gesture. She dutifully retrieved the sonic screwdriver and handed it to him through the force field.

He fiddled with it for a while, his work punctuated by mutterings of "This is never going to work," and, "It's a _screwdriver_, for heavens' sake." Finally he pointed it at a spot in the corner of his room.

ZAP!

The Master appeared, collapsed on top of a splendid gold shield. The Doctor stared first at the Master and then, very incredulously, at his sonic screwdriver.

"Told you," said Rose.

"Amazing," he said, gazing at the screwdriver with bright, feverish eyes. "You know...I think I could get this to do all _sorts_ of things..."

After marveling at the screwdriver a few moments longer, the Doctor climbed out of bed, scattering nursebots. He staggered towards the Master. "Your plan seems to have backfired. You've no choice now, you must help us." He crouched down and seized the Master's shoulders, shaking him. "Give me the antidote!"

The Master opened his eyes and laughed hollowly. "The antidote? I haven't got it."

The Doctor stared at him in disbelief. "Only the most arrogant fool would unleash an epidemic and not have the--"

"I didn't unleash it," hissed the Master. "I had nothing to do with it!"

"But...but you confessed!"

"I confessed under i _torture /i _! I've been accused of so many crimes, what was one more? I was willing to say anything to make it stop." The Master collapsed again. A swarm of nursebots hoisted him up, and deposited him in one of the adjoining ICU beds, leaving the shield behind.

The nursebots tugged on the Doctor's hospital gown, guiding him back to bed. He began to follow them; then stopped suddenly, gazing at the shield. "Caligarian!"

Dr Caligarian, paralysed by the shock of seeing the Master appear, recovered slightly upon hearing his name. "Yes, Doctor?" he squeaked.

"How did this epidemic start?"

"Oh…well, the very first cases were the entire temporal archeological team—"

"The team that journeyed two million years into our past, and brought back the shield of Rassilon." The Doctor's eyes were shining. "The shield that was hanging in Councillor Romana's office. The shield that the Master was clutching. The 'ultimate weapon' he called it..."

"So it's some kind of bio-weapon?" asked Rose.

"No!" cried the Doctor, swaying slightly. Rose was behind him in an instant, steadying him. "A bio-weapon kills indiscriminately. Rassilon would never have made such a…" He snapped his fingers. "Caligarian! What was that you said about Rose? Her primitive immune system? A primitive immune system might be just the thing to battle primitive parasites! Parasites _so_ primitive, we don't even think to scan for them on the TARDIS biofilters. Parasites that perhaps...perhaps just i _happened /i _ to hitch a ride on Rassilon's shield..."

The Doctor's knees began to buckle. Rose helped him back to bed, and the nursebots reformed their silver web about him. In a weak voice, he continued, "Caligarian, she went through Customs, her blood prior to infection is on file, see what you can..."

"Yes, Doctor, yes! I know what you want," cried Caligarian. "Human, come here!"

"My name's Rose," she said, sharply, as she raced up to the command center.

"Please, sorry, I need some of your blood." As she nodded her assent, the nursebots extracted a vial of blood from her arm. Dr Caligarian snapped it into a rotating machine, then punched up two overlapping images of her blood cells. He stared at the images for a moment, becoming increasingly puzzled. "What are those?" He pointed to a spherical cell packed full of tiny granules. There were only one or two of these cells in her Customs blood sample; but they were everywhere in her current one. "These cells are part of your immune system; they expanded to fight off the infection…but I don't recognise this cell type." He tapped at his console. "Checking the database…and…I don't believe it…yes! YES! Eosinophils!"

"What? What's an eosino--" asked Rose.

Caligarian was literally jumping up and down. "Eosinophils! They used to be responsible for scores of asthma-related regenerations in Time Lords, until we had them removed from our genome."

"And…that helps us how, exactly?" Rose was now utterly confused.

"They only cause asthma in civilised societies, when they can't do their real job." He increased the image magnification until a single cell covered the entire field. "See all those toxic granules? Eosinophils migrate right next to their prey and release them. They attack parasites! Worms! Search and destroy!"

Dr Caligarian turned to his console, muttering to himself. "Cloning...expanding... altering MHC..." There was a buzzing noise, and then he pulled a vial of shimmering liquid from the apparatus. He regarded it for a moment. "Here it is but...I don't know...the species variation might make it as lethal as the worm..."

"Let me see," commanded the Doctor. Dr Caligarian handed him the vial through the force field. The Doctor held it up to the light, shook it slightly, and passed it under his nose, as one might smell a fine cigar. Suddenly, he flipped open the head of the nearest nursebot, snapped in the vial, then used the nursebot's syringe attachment to inject it into his arm.

"NO!" cried Dr Caligarian. "I haven't tested it yet!"

An alarm shrieked. The Doctor's 3-D image flickered wildly on the command console. Despite Dr Caligarian's desperate ministrations, the image flashed and went out.


	6. Chapter 6

Flanged helmets, high collars and robes: the Time Lords processed past in a somber line. The tuneless music sounded a seemingly endless dirge. On a high altar, the Time Lords circled, with bowed heads, reciting solemn, incomprehensible incantations. Rose's head nodded; the rite had gone on for what seemed like hours.

A voice whispered sternly in her ear, "You are the first off-worlder ever to see the Ceremony of Thanksgiving, so show proper respect: if you fall asleep, try not to snore." Rose glanced up. The Doctor winked at her, then pointed out an elderly Time Lord who was fast asleep and snoring. She was suddenly and inexplicably overwhelmed with the urge to laugh; she bit her lip and stifled it, with limited success. Her body rocked with silent giggles. Romana, seated on the other side of the Doctor, turned and glared at them. The Doctor arranged his face into an expression of complete innocence. This of course made Rose want to laugh even harder.

At long last, the ceremony was over, and the Time Lords spilled out into an adjacent reception hall. The Doctor tried to slip away, but was soon caught up in a sea of congratulatory well-wishers. Dr Tinklepaugh clapped him on the shoulder, "Well, it was touch-and-go there for a while; but what a genius idea, a real stroke of brilliance..." His voice was drowned out by the noise of the hall. Soon the crowd separated Rose and the Doctor, and she was left alone.

"Hey, it was my blood that cured everyone," she wanted to say. However, her contribution seemed to have been largely forgotten. She headed towards the punch bowl. An elderly Time Lord--the one who had been snoring throughout the Ceremony--intercepted her. He introduced himself as Chronotis, President of Gallifrey. He thanked her graciously for her help in combatting the epidemic.

Rose saw her opportunity. There was something she desperately wanted: something the Doctor had said by chance that hadn't registered at the time, but had been burning in her heart ever since. "Can I ask a favour? I need a Dimensional Visa." She explained about her world and the Time War. President Chronotis listened gravely.

"I am sorry," he said quietly. "But until there is a sufficient complement of Time Lords to guard the Void in your universe, it would be highly unwise to open a rift."

She opened her mouth to protest; but then asked, "Wait—'until?' Did you mean 'until'...as in, there might be more Time Lords there one day?" But the president had already wandered off.

"Hard luck, I'm sorry," said the Doctor, appearing behind her and patting her shoulder. "Hang on a minute, I'll be back." She watched him go. He moved off into the crowd and disappeared.

"Um...hello?" said a voice. She turned around. A tall, gangly, young-appearing Time Lord was standing before her, smiling bashfully. He had bright blue eyes and a mop of unruly black hair. "Didn't mean to disturb you. I just wanted to say...your blood cured my mum. She was on the archeological team. Thanks."

"Oh, no problem. Happy to do it. I'm glad she's doing well." She smiled at him. He smiled back. There was an awkward pause. They giggled.

"I'm Rose," said Rose. "What's your name?"

"Timethesra'am. But...um...you can call me Tim."

"Hi Tim," said Rose. There was another pause.

"Um..." he glanced away. "Would you...um..." He swallowed. "Would you like to see my TARDIS?"

"Seriously?" she grinned.

"Yeah...it's...well, the Doctor has an old Type 40, it's a classic, we took one apart in shop class, but...I got a 280-zx for my birthday. It's brilliant. Want to see?"

"You got a TARDIS for your birthday? How old are you?'

His cheeks flushed scarlet. "I'm...21."

"Twenty-one? Not 121 or 221 or 1221?"

"Yeah...I'm a kid. I'm sorry, I'll stop bothering you." He turned to go.

"No," Rose said, reaching for his arm. "I'll come and see your 280-zx. Why not?"

"Brilliant!" he said, beaming. "Come on, it's this way."

A moment after Rose and Tim left, the Doctor reappeared, with Romana following. He was holding two glasses of punch. He looked about and frowned. "She wandered off. Why do they _always_ wander off?"

Romana clucked her tongue disapprovingly. "These humans are but children. Children wander. The fault is yours for never looking after them properly."

Tim's TARDIS was completely invisible from the outside, which might have been more impressive had he been able to find it without stumbling into it. Rose stepped inside. There was none of the accumulated dust and clutter that characterised the Doctor's TARDIS, no bookcases extending to the ceiling, nor the collection of odd tools strewn about, required for constant repairs and tinkering. She admired the minimalist, matte silver interior and the sleek, streamlined control panel. There was a glint of something gold in the corner. "It's lovely," said Rose.

The doors clicked shut. "I am so glad you like it, as I anticipate you'll be spending a great deal of time here as my...guest."

The hairs on the back of Rose's neck stood up. She whirled around. In place of the gangly youth was an older man staring at her with a nasty glitter in his eyes.

"Where's Tim?" she asked.

"I am Tim. But I'd prefer it if you called me Master."


	7. Chapter 7

"Master?" Rose gasped.

"Yes, that's right. _Master_. Has a nice ring to it, don't you think?" He casually reached for the console and flipped a lever. The central shaft lit up.

"No!" shouted Rose. "I don't want to go anywhere. Let me out!" She lunged for the door.

But the Master had already set his TARDIS in motion. "Tut tut, my dear. There's no need to be rude. You may step outside, if you insist. But I'm afraid it will be a one-way trip."

Rose let go of the door handle. She turned towards the Master and scowled deeply at him, her fists clenched. "This isn't funny," she hissed. "Take me back, right now!"

"In time, little one, in time. I've one or two things to attend to first."

"Like WHAT?"

"Oh...exacting a bit of revenge," said the Master, with a satisfied smile. "The Time Lords tortured me. I shall obliterate them from existence. A reasonable exchange, don't you think?"

Rose gaped at him. "You...you...you can't. You're joking!"

"Not at all. Only recently, the Time Lords made it very easy to travel back and forth in Gallifrey's ancient history. Ergo, it will be a simple matter indeed for me to destroy Rassilon, thus preventing the rise of the Time Lords--the only race in the universe who could possibly imprison me, harm me, or hinder me in any way. Therefore they must be destroyed."

"But you're a Time Lord, too, aren't you? If you prevent their development, won't that destroy you?"

The Master frowned, but didn't reply, as if he hadn't quite considered that possibility.

Feeling somewhat encouraged, Rose went on, "If you want a universe without any Time Lords, it's simple. Piece of cake. I'm from a parallel universe where all the Time Lords were killed in a war. All you have to do is open up a rift, and there you are."

"Is that really so? No Time Lords?" said the Master, his dark eyes shining. "Excellent! Then parallel pressure makes my task here that much more straightforward."

"Parallel...pressure?"

"You are a very stupid child. In highly simplified terms, it means that if the Time Lords have died in your parallel universe, they are more easily destroyed in mine. And that includes the Doctor."

"No," said Rose. "He'll find a way to stop you."

"Possibly, possibly," agreed the Master, with a wry smile. "He does often manage to thwart my plans. However, by significantly deranging the timeline, I may well destroy his most powerful weapon."

"He never carries weapons," Rose said quickly, then regretted it.

"Yes, yes I know," he said, waving her off dismissively. "I was referring to his mind; or, more precisely, his memory."

"You're mad," said Rose. "He's the most absent-minded--"

"Absent-minded or no, the Doctor can remember the future. It has taken me a very long time to work it out: but the reason he always seems to hit upon the right solution; the reason he, despite impossible odds, always seems to prevail; and the reason he persists in beating _me_, despite my vastly superior intellect, is that he can remember what is going to happen. He doesn't remember it consciously, of course; but the talent is sufficient that he can usually intuit the right course of action. In any case," the Master added, "even if altering the timeline doesn't do the trick, I have other means of destroying him..."

"Well, this is all _really_ interesting, but why bring me along? Won't I get in your way?"

"I brought you here principally out of spite. It will distress the Doctor tremendously when he discovers I've taken one of his companions, especially as he has no means of rescuing you."

"No, we've only just met," Rose protested. "He doesn't care about me, he won't miss me--in fact, he probably won't even notice I'm gone."

"Wrong on three, Rose." The Doctor stepped into the Control Room, and gazed at her with a wounded expression. "I realise it's only been a few days, but surely you know me better than that."

"Doctor!" cried Rose, in ecstatic relief.

"Doctor!" cried the Master, under the influence of somewhat different emotions. "How--how did you find--"

"You didn't really think that the Time Lords would allow you to escape a maximum security prison _and_ the hospital without putting a homing beacon on your TARDIS? All I had to do was rig a little device to track you through the Time Vortex and transmat onto your TARDIS." He twirled his sonic screwdriver through his fingers and winked at Rose.

The Master's jaw dropped. He sputtered for a moment, then snarled, "No matter! You are here, in my power, exactly where I want you."

"In your power? Ha! All that nonsense you spouted about my remembering the future? You might try to remember the past. You can never beat me, I am--"

"Your little friend reminded me that you are always unarmed," said the Master, silkily. He snapped his fingers. A long, black, pointed probe slid into his hand.

The Doctor's eyes widened, and he faltered for a split second. Then, recovering himself, he said, "If you think a dendritic disruptor is going to frighten me, you are very much--"

"Brave words, Doctor." He smiled unpleasantly. "However, I think the prospect of having your mind ripped away piece by piece--and being aware of it as it happens--frightens you very much."

"N-no," said the Doctor, backing away, "_you_ are the one who should be afraid. I've proven over and over again that I don't need illegal weapons to defeat you, and that--"

"And the other thing I remember, Doctor, is NOT TO LET YOU TALK!" The Master squeezed his probe, which sent out a black plume of energy. The Doctor immediately ducked and sprang away. But there was little cover in the open, uncluttered control room. Desperately, the Doctor clutched at anything that might block the Master's barrage. His fingers closed on the handle of a golden shield, which had been propped up in the corner. He held the shield up in front of him, just barely blocking another black energy plume.

At that moment, the golden shield began to vibrate, filling the room with a clear, bell-like tone. The tone settled into a standing wave about the Doctor. Every plume of energy the Master fired at the Doctor was disrupted and dispersed.

"Aha! Rassilon's ultimate weapon," the Doctor exclaimed gleefully. "The best offense is a perfect defense. I knew there was a reason I was fond of Rassilon, apart from his discovering time travel, establishing our society..."

"I know your weakness," hissed the Master. He caught hold of Rose. "Throw down the shield, Doctor, or I destroy her mind."

"Don't do it, Doctor!" cried Rose.

"I...I'm putting it down," said the Doctor, releasing his grasp. The shield fell to the floor with a clang.

"Now," said the Master, pointing his probe at the Doctor, who swallowed hard. "Finally, I shall be the one doing the talking. You, Doctor, have the unique distinction of being my most worthy adversary. I confess...some part of me is sorry to see it all come to an end. But, finally, inevitably, you have lost. And I mean to make my victory over you complete. First, I will destroy your companion's mind, and you will witness her agony. Then I will destroy yours, and you will feel yourself--excruciatingly--wither away to nothingness. Finally, I will totally and utterly eradicate the Time Lords from existence. And there is absolutely nothing you can do to stop me!"

"No, perhaps I can't," said the Doctor, who had been secretly retrieving something from his pocket during the Master's speech. "But _they_ can." He bowled a white sphere at the Master. It cracked open instantly, emitting more spheres. They rose up on metal legs and swarmed.

"NO!" cried the Master, trying vainly to bat them away. Rose wrestled from his grasp. The Doctor caught her in his arms and swung her away.

"Nursebots!" gasped Rose, "Did you..."

"Yes, I...might have reprogrammed them...ever so slightly," said the Doctor, a smug smile playing at the corners of his lips.

The nursebots unhooked the Master's trousers and took down his pants. Amid his screams of protest, one drove its enormous syringe attachment into the Master's backside. He yelped once; and then collapsed, unconscious.


	8. Chapter 8

Despite returning in triumph bearing the anaesthetised Master, the Doctor managed to beg off any further celebratory ceremonies. He made his good-byes. Councillor Romana saw them off.

"Are you coming with us?" asked Rose.

"Oh, no," laughed Romana. "I travelled with the Doctor once...but that was a very long time ago."

The Doctor gazed at her fondly for a moment; then stopped and looked about, clearly confused. "Where's my TARDIS? I left it right here."

"Oh, that's a surprise," said Romana, smirking. "A token of our gratitude. We fixed the chameleon circuit. It is now completely invisible."

"But I didn't _want_ the circuit fixed--I like the police box! You know that very well, Romana!" cried the Doctor agitatedly. "How am I supposed to find it?"

"You'll manage, I'm sure. Good-bye, Doctor. Good-bye Rose." Romana waved and left.

Muttering irritably to himself about upstart, impudent, teasing Time Ladies, the Doctor began feeling about for his TARDIS. "OW!" he cried, stubbing his toe. Then he disappeared.

"Doctor?" called Rose. "Where are you?"

A vertical sliver of TARDIS interior appeared in mid-air, then widened. "Right here," said the Doctor, hopping on one foot in the doorway. "Watch your step."

"I have a question," said Rose, as she made her way inside.

"What is it?" answered the Doctor, as he began checking the TARDIS controls.

"I still don't understand where all those parasites that caused the epidemic came from. It was something to do with the shield, I know, but...you said it wasn't a bioweapon."

"One of the perils of time travel is that sometimes you pick up hitchhikers." He winked at her. "Only in this case, the parasites were hitching a ride on Rassilon's shield. Two million years ago, I suspect they were everywhere, but Gallifreyans had a natural immunity to them. But since then, the parasites died out and consequently our immunity waned. Which reminds me--" He snapped his fingers. "If I ever take you back to pre-20th century Earth, we've got to make sure you've had all your shots."

"Okay..." said Rose, not at all enthusiastic about the prospect.

"Now, where to, where to?" said the Doctor, stroking his chin. "Enough of boring, crusty old Gallifrey, how about--"

"I have another question," Rose interrupted. "What is 'parallel pressure'? You talked about it when you were delirious, and the Master said it would make it easier for him to destroy the Time Lords."

The Doctor's expression turned grave. "It is a property of parallel universes. Every time you make a decision; every time an event could go one way or another, it draws in the Void and creates a new parallel universe, one for every possible outcome. Thing is--most decisions turn out pretty similarly in the end. So the divergent parallel universes eventually collapse together again, driving out the Void. Are you with me so far?"

"Er...yes," said Rose. "Sort of."

"Very large events, however, such as the death of the Time Lords in one universe, create a sort of 'pressure' on adjacent parallel universes, pressure for a similar event to occur in the adjacent universe, so that they can collapse together again in the future. I was concerned that the contagion was a manifestation of this pressure, perhaps leading to the weakening and death of the Time Lords in this universe."

Rose puzzled over this for a moment. "But...if the Time Lords are alive in the other universes, and mine is the only one where they're gone...shouldn't the pressure be in the opposite direction? Shouldn't there be pressure for the Time Lords to return?"

"Very good, very clever," said the Doctor, smiling. "Yes, and that is a happy thought."

Rose nodded, then said, "I have one more question."

"I had a feeling you might."

"It's something the Master said. Can you really remember the future?"

The Doctor laughed. "What a preposterous idea. You are a very silly girl, Rose Tyler."

Rose scowled. "Well, I just thought...hang on! I never told you my last name is Tyler."

"Of course you did."

"When?"

"Just now."

"Doctor!"

_Many thanks to everyone who has taken the time to review. I write principally for my own amusement, but it's great to be able to entertain others as well. _

_Stay tuned for the next story in this series: "The Restaurant at the End of the Multiverse"_


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